The display uses two synchronized peristaltic pumps to push water and red paraffin through a tube that switches back over itself in a predictable fashion. As visible in the video after the break, the pumps go at it for a few minutes producing a seemingly random pattern. The pattern coalesces at the end into a short string of text. The text is unfortunately fairly hard to read, even on a contrasting background. Perhaps an application of UV dye could help?

Once the message has been displayed, the water and paraffin drop back into the holding tank as the next message is queued up. The oil and water separate just like expected and a pump at the level of each fluid feeds it back into the system.

We were deeply puzzled at what appeared to be an Arduino mounted on a DIN rail for use in industrial settings, but then discovered that this product is what [hwhardsoft] built the demo to sell. We can see some pretty cool variations on this technique for art displays.

Here at Hackaday, we often encourage people to hack for the greater good through contests. Sure, it is fun to create a wireless barbeque thermometer or an electronic giant foam finger. At the end of the day, though, those projects didn’t really change the world, or maybe they just change a little corner of the world.

I recently saw a commercial device that made me think about how more hacker-types (including myself) ought to be working more on big problems. The device was Watly. The Italian and Spanish start up company claims the car-sized device is a “solar-powered computer.” No offense to them, but that’s the worst description for Watly that you could pick and still be accurate.

So what is Watly? It looks like some sort of temporary shelter or futuristic campsite equipment. However, it contains an array of solar cells and a very large battery. I know you are thinking, “Great. A big solar charger. Big deal.” But there’s more to Watly then just that.

The first Watly rolled out in Ghana, in Sub-Saharan Africa. About 67% of the population there–over 600 million people–do not have electricity. Nearly 40% do not have safe water. Watly uses a graphene-based filter and then uses its electricity to distill safe drinking water by boiling it. The company claims the device can deliver about 5,000 liters of safe drinking water per day.

If you read Hackaday, it is a good bet you have easy access to safe drinking water, electricity, and Internet. Think for a minute what it would be like if you didn’t. Here on the Gulf Coast of the United States, we sometimes have hurricanes or other storms that show us what this is like for a week or two. But even then, people come with water in trucks or cans. Generators show up to let you run your fridge for a few hours. Even more important: you know the situation is only temporary. What if you really thought those services would never be restored?

The portable device can provide power, water, and wireless Internet service and can last for 15 years. Watly intends to create a larger version with even more capacity. The project received funding from the EU Horizon 2020 program that we’ve mentioned before. Creating clean water is something that can help lots of people. So is using less water. If you want some more inspiration for tackling water problems, we’ve got some links for you.

For her science fair project, [David]’s daughter had thoughts about dipping eggs in coffee, or showing how dangerous soda is to the unsuspecting tooth. Boring. Instead she employed her father to help her build a Morse Code waterfall.

A more civilized wea– tool from a more elegant age. Young Jed–Engineer.

[David] worked with his daughter to give her the lego bricks of knowledge needed, but she did the coding, building, and, apparently, wire-wrapping herself. Impressive!

She did the trick with two Arduinos. One controls a relay that dumps a stream of water. The other watches with an optical interrupt made from an infrared emitter and detector pair to get the message.

To send a message, type it in the keyboard. The waterfall will drop spurts of water, and then show the message on the decoder display. Pretty cool. We also liked the pulse length dial. The solution behind the LEDs is pretty clever. Video after the break.

A few motors, propellers, a camera, maybe a wire tether, and some waterproof electronics. Throw it all together and baby you’ve got an underwater Remotely Operated Vehicle (ROV) cooking! It all sounds simple on the surface, but underwater ROVs are a tough challenge. We’ve all seen deep-sea ROVs searching the wreck of the Titanic, or working to stop the flow of oil below the Deepwater Horizon. Plenty of hackers, makers, and engineers have been inspired to build their own underwater ROVs. This week on the Hacklet, we’re spotlighting at some of the best ROV projects on Hackaday.io!

We start with [Tim Wilkinson] and BorgCube ROV. [Tim] has jumped into the world of underwater ROVs with both feet. BorgCube is designed to operate in the unforgiving salt waters of the Pacific Ocean. This ROV can see in stereo, as [Tim] plans to use a head mounted VR display like the Oculus Rift to control it. [Tim] wanted to use a Raspberry Pi as the brains of this robot. Since the Pi Compute module can handle two cameras, it was a natural fit. The electronic speed controls are all low-cost Hobby King R/C car units. [Tim] created a custom circuit board to hold all 12 ESCs. This modular design allows individual controllers to be swapped out if one meets an untimely doom. BorgCube is just getting wet, but with 37 project logs and counting, we’re sure [Tim] will keep us posted on all the latest action!

Next up is [MrCullDog] with Luna I ROV. Inspired by a professional underwater ROV, [MrCullDog] decided to build a deep diving unmanned vehicle of his very own. Like BorgCube above, many of Luna I’s motors and drive components come from radio controlled hobby electronics. [MrCullDog] is bringing some 3D printed parts into the mix as well. He’s already shown off some incredibly well modeled and printed thruster mounts and ducts. The brains of this robot will be an Arduino. Control is via wired Ethernet tether. [MrCullDog] is just getting started on this project, so click the follow button to see updates in your Hackaday.io Feed.

Next up is [Edward Mallon] with The Cave Pearl Project. Not every underwater system needs motors – or even a human watching over it. The Cave Pearl Project is a series of long duration underwater data loggers which measure sea conditions like temperature and water flow. [Edward’s] goal is to have a device which can run for a year on just three AA batteries. An Arduino Pro Mini captures data from the sensors, time stamps it, and stores it to a micro SD card. If the PVC pipe enclosure keeps everything dry, the data will be waiting for [Edward] to collect months later. [Edward] isn’t just testing in a swimming pool, he’s been refining his designs in open water for a couple of years now.

We are all used to turning on the faucet and having clean, drinkable water on demand. But think about what happens afterwards in your home: that water is used to wash dishes or water lawns and many other uses that render it undrinkable. What stops this nasty water from flowing back into your pipes and out of your kitchen faucet? A backflow preventer. This simple, but vital, part of your plumbing turns your water pipes into one-way systems that give out clean, drinkable water. This isn’t just about making your water taste nice: backflow preventers protect your water supply from things like brain-eating amoeba and E Coli that could kill.

[mulcmu], we suppose, frequently wastes a lot of water while daydreaming in the shower. While daydreaming in the shower one day, we suppose again, he came up with the idea of keeping on task while in the shower. Thus was born the shower metronome, [mulcmu]’s entry for The Hackaday Prize.

The goal of the shower metronome is two-fold. First, it reduces the amount of water used in the shower. Secondly, it keeps the user on time for work. The shower metronome does this with a small audio beep provided by a small microcontroller attached to the shower frame or shower curtain.

The guts of the device are an MSP430 microcontroller, a few coin cell batteries, and a hall effect sensor that turns the device on, just like a magnetic door or window alarm. The microcontroller choice is perfect for the application; the MSP430 is extremely low power, and the device only draws 1uA in low power mode. This means the shower metronome will last a while when used only a few minutes a day.

Water: Life on earth wouldn’t exist without it. 71 percent of the Earth is covered by water. That only leaves 29 percent for us humans to live – and not all of that land is inhabitable. Water is so important that most human settlements start near water of some sort. Water to drink, or water to move goods. With all this water in oceans, lakes, and rivers, it is no surprise that hackers, makers, and engineers alike build some incredible projects that work on and under the water.